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121.
从目前使用中的特种设备存在的诸多安全问题入手进行分析,给出了比较切合实际的解决问题的方法,对现实的生产活动有很强的指导作用。 相似文献
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123.
This study investigated the particulate matter (PM) and metals in highway dry deposition and rainfall-runoff as a function of hydrologic transport and settling on an event basis. Events were differentiated as mass-limited (ML) and flow-limited (FL). Results indicate that unique and separate suspended sediment concentration (SSC) relationships with turbidity occurred for ML and FL events. Sixty minutes of quiescent settling produced a single SSC-turbidity relationship for all events. ML events transport higher proportions of settleable and sediment PM while FL events transported relatively higher suspended PM. For batch clarification with one hour of settling, ML events had generally higher treatment efficiencies compared to FL events for the same settling conditions. Highway dry deposition PM was hetero-disperse and coarse (d 50 m = 304 μm). Results indicate that the acidic rainfall is not a significant contributor to metals in runoff but is capable of leaching metals from dry deposition PM into runoff. Partitioning in retained runoff resulted in a particulate-bound predominance for most metals except Ca and Mg. While the finer fraction of dry deposition PM (< 75 μm) generates the highest metal concentrations, the highest metal mass is associated with the coarser fraction (> 75 μm). 相似文献
124.
This study investigated the association between vaccination with the Hepatitis B triple series vaccine prior to 2000 and developmental disability in children aged 1–9 years (n = 1824), proxied by parental report that their child receives early intervention or special education services (EIS). National Health and Nutrition Examination Survey 1999–2000 data were analyzed and adjusted for survey design by Taylor Linearization using SAS version 9.1 software, with SAS callable SUDAAN version 9.0.1. The odds of receiving EIS were approximately nine times as great for vaccinated boys (n = 46) as for unvaccinated boys (n = 7), after adjustment for confounders. This study found statistically significant evidence to suggest that boys in United States who were vaccinated with the triple series Hepatitis B vaccine, during the time period in which vaccines were manufactured with thimerosal, were more susceptible to developmental disability than were unvaccinated boys. 相似文献
125.
在建筑火灾和一些紧急突发事件中,特殊人群不能使用正常人的紧急疏散通道,也不能达到正常人的疏散速度,而这个问题在目前的消防设计和消防规范中基本上没有得到解决.在分析特殊人群疏散行为规律的基础上,选取医院住院楼的标准层进行了疏散模拟,得出了一些重要结果,对疏散设计具有指导作用.最后提出了特殊人群的疏散设计方法,主要包括AORS系统和特殊报警系统的设计. 相似文献
126.
苯酚存在对生物强化系统降解2,4-二氯酚的影响 总被引:5,自引:1,他引:4
研究了采用生物强化技术降解废水中2,4-二氯酚(简称2,4-DCP)时,不同浓度的苯酚存在对生物强化系统降解2,4-DCP的影响,并通过半连续流实验研究了苯酚长期存在下强化系统中2,4-DCP和苯酚生物降解速率的变化趋势.结果表明,苯酚浓度为10mg/L,50mg/L,100 mg/L及300mg/L时,都会对强化系统中2,4-DCP的降解速率产生一定的抑制作用,而且抑制作用随着苯酚浓度的增加而增强.不同浓度的苯酚与2,4-DCP长期共存时,2,4-DCP的降解速率表现出下降的趋势,而苯酚的降解速率则有所增强. 相似文献
127.
Operating several assets has resulted in more complexity and so occurrence of some major accidents in the refining industries. The process operations risk factors including failure frequency and the consequence components like employees' safety and environment impacts, operation downtime, direct and indirect cost of operations and maintenance, and mean time to repair should be considered in the analysis of these major accidents in any refinery. Considering all of these factors, the risk based maintenance (RBM) as a proper risk assessment methodology minimizes the risk resulting from asset failures. But, one of the main engineering problems in risk modeling of the complex industries like refineries is uncertainty due to the lack of information. This paper proposes a model for the risk of the process operations in the oil and gas refineries. The fuzzy logic system (FLS) was proposed for risk modeling. The merit of using fuzzy model is to overcome the uncertainty of the RBM components. This approach also can be accounted as a benchmark for future failures. A unified risk number would be obtained to show how the criticality of units is. The case study of a gas plant in an oil refinery is performed to illustrate the application of the proposed model and a comparison between the results of both traditional RBM and fuzzy method is made.For the case study, 26 asset failures were identified. The fuzzy risk results show that 3 failures have semi-critical level and other 23 failures are non-critical. In both traditional and fuzzy RBM methods, some condenser failures had the highest risk number and some pumps were prioritized to have the lowest risk level. The unit with unified risk number less than 40 is in the non-critical conditions. Proposed methodology is also applicable to other industries dealing with process operations risks. 相似文献
128.
为了对铁路专用线危险货物运输安全性进行科学合理的评价,系统分析了铁路专用线危险货物运输特征及影响因素,从“人、机、路、管”角度出发,构建了涵盖资质管理、安全设备设施、运输设备设施、安全管理4个层面的铁路专用线危险货物运输安全评价体系。针对指标间存在的冗余性问题,采用基于改进区分矩阵的粗糙集属性约简算法对评价体系进行精简,并以成都铁路局某条危险货物专用线进行实例研究。结果表明:托运人资质、安全监控系统等10项指标为属性约简后的重要风险因素。 相似文献
129.
某油田污水处理站设计处理规模1500 m3/d,实际处理量630 m3/d,处理工艺为“微生物接触氧化+加药絮凝沉淀+二级过滤”,在运行过程中投加的混凝剂等药剂成本高,且二级过滤器使用年限过长,其处理后出水无法达到Q/SYTH 0082—2020《油田注水水质规定》中油小于5 mg/L、悬浮物含量小于3 mg/L、粒径中值小于2μm的注水水质要求。该油田污水处理站开展了“特种微生物+低能耗管式膜”污水处理技术研究,并完成现场中试试验,处理后膜出水的悬浮物含量基本稳定在1 mg/L,出水水质达标,表明此工艺处理油田污水是可行和可靠的,为该油田污水处理工艺优化提供了可靠依据。 相似文献
130.
为了厘清地下洞室群施工现场作业风险因素间的关联效应,利用AMOS软件构建施工风险影响因素结构方程模型,对已建模型进行验证性因子分析,利用计算得出的M.I值对已构建的模型进行修正。根据所得模型计算出的路径系数和方差,对地下洞室群施工风险因素关联效应进行分析。结果表明:规章制度建设及执行、围岩稳定性、进场设备优良率、工人技术等级、工人逆反心理以及消极作业分别为各风险层次中影响最大的风险因素,且各风险层次间的关联效应表现出耦合关系;现场作业风险因素可分为现场主体因素、现场客体因素和现场控制因素3大类,它们之间成向量关系,以此为基础建立向量模型,可清晰直观地展示3大因素之间的主次关系。 相似文献